My group would like to meet monthly and possibly use the rear section of the restaurant. The amount of participants will be 10-20 adults. Do we need a reservation ? Do you provide a minimuzed menu for groups?

I am unsure of how this work, but you calling to het a better perspective

I don't know exactly how their reservations go but on Thursday nights they have kareoke and Fridays its dancing and music so you wouldn't probably be able to reserve that area on those days.

I do not work for Denny's I would suggest you contact any resturant in regard to making ANY party over 5 people

Getting a reservation is a must to have seating available for that size group.